Solar challenge: a competition showcasing solar homes puts energy-efficient construction in the spotlight - Construction Products

Building Products, May-June, 2003 by Stephani Miller

College students from across the country want builders and homeowners to know that sun-powered homes are really cool.

To promote solar energy as a viable alternative, the U.S. Department of Energy along with several building product manufacturers and other groups sponsored the Solar Decathlon, an event that pitted J4 teams of architecture and engineering college students against each other to see which could design and build the most energy-efficient, aesthetically pleasing house powered entirely by solar energy. The students were charged with using existing products and materials, and the houses were limited to S00 square feet.

DOE was keenly interested in this competition, officials say, because of the electricity crisis in California, the rising costs of natural gas, and the war and continuing turmoil in the oil-exporting Middle East. "Energy efficiency and solar technologies are available for the home, and they are affordable," DOE Secretary Spencer Abraham said in a statement about the event.

Besides DOE, the other Solar Decathlon sponsors were BP Solar, The Home Depot, Electronic Data Systems, and the American Institute of Architects.

For two weeks last fall, the students' solar-powered houses were evaluated by architects and government energy experts and toured by the public in Washington, D.C. The tiny dwellings were judged on 10 criteria, including design, livability, interior comfort, and energy-efficient lighting and heating/cooling. The buildings also had to generate enough excess electricity to power a small electric vehicle.

The winning team from the University of Colorado at Boulder found off-the-shelf products or materials in every category that met the requirements, and said that the items were priced comparably to conventional ones.

For solar energy, the Colorado students chose photovoltaic roof panels manufactured by AstroPower. A standard AstroPower solar energy system of 24 photovoltaic modules can generate nearly half the power consumed by a typical four-member household, according to the company.

SUNTube solar thermal evacuated tubes made by Sun Utility Network were selected to collect solar heat for the house's hot water system. In this system, solar energy is gathered, converted to heat, and then transferred to water stored in the tubes.

For the skylights, the Colorado team chose Primalite glazing because it reduces heat-transmitting solar energy while letting in lots of visible light. According to Brian Cross, technical support manager at PolyGal USA, maker of Primalite, the glazing "will reduce the sun's near-infrared energy so that the interior of the space is cooler."

Daylighting played a large part in the Colorado team's design. To reduce the home's heat gain, the students speced windows with HeatMirror insulating glass by Southwall Technologies. "As you increase daylighting, you increase the amount of solar heat gain, and that creates a problem," says Graig Young, vice president of architectural products worldwide for Southwall Technologies, which claims HeatMirror reduces heat gain by as much as 50 percent.

Other teams also found readily available solar products that suited the requirements. For example, the Crowder College team installed panels from BP Solar and the University of Virginia team used ASE Americas panels.

Although solar energy represents only a tiny part of America's energy supply, the demand for solar panels increased by 20 percent each year during the past four years, according to the DOE. "Energy is presently a high-cost item," says Les Hamasaki, executive vice president and sustainable development planner for Sun Utility Network. Solar energy "is provided free," he says.

Bright Ideas

The students who participated in the Department of Energy's Solar Decathlon learned a lot about constructing energy-efficient homes. Here are 10 suggestions the university teams have for everyone involved with building houses.

* Use foam insulation instead of fiberglass. The expanded foam allows you to seal off all the gaps in the house.--University of Missouri-Rolla

* SIPs (structural insulated panels) are amazing because of their high R-values and super-tight construction. And they arrive waiting to be pieced together, so you save construction time and there is less waste.--University of Maryland

* Geothermal heat pumps are the most efficient way to heat and cool a house.--University of Virginia

* By using a radiant floor, a solar hot water system heats both the living space and the water for domestic consumption. The payback period is much quicker for solar hot water than for photovoltaics.--University of Maryland

* One of the easiest things is to place windows on the south side of the house. And by adding shades, you almost don't need an HVAC system. --University of Missouri-Rolla

* It's crazy how much people spend each year on incandescent lights. Use fluorescents.--University of Virginia

* Adding energy-efficient appliances makes your whole system more efficient.--Texas A&M University

* Choose your appliances and lighting wisely. Lighting and appliances are used on a daily basis, so the savings add up over the lifespan of the products.--University of Maryland